Technical Field
The present disclosure relates to a flow path structure of a power transmission device which removes gas from a lubricating fluid guided to a fluid reservoir inside a casing of the power transmission device.
Related Art
Conventionally, as a power transmission device mounted in a vehicle or the like, there is a power transmission device including a transmission which shifts a speed of a driving force of an internal combustion engine and then outputs the driving force, a differential device which distributes the driving force output from the transmission to left and right driving wheels, and a transfer device which distributes the driving force transmitted to the differential device to other driving wheels located in forward and backward directions.
In this type of power transmission device, lubricating oil stored in a casing is suctioned up by a pump via a strainer and is supplied as lubricating oil to built-in components of the power transmission device, or is used as a working oil pressure for a hydraulic operation device (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2014-119055).
However, in the conventional power transmission device as described in JP-A No. 2014-119055, if the pump suctions air together with the lubricating fluid such as lubricating oil from an oil reservoir (fluid reservoir), there may be a problem that a required working pressure cannot be supplied.
To prevent this, it is conceivable to perform a process in which the gas is removed from the lubricating fluid guided to the fluid reservoir using a defoaming device. However, when the defoaming device for removing the gas from the lubricating fluid is additionally provided, a size of the entire power transmission device may be increased.